1. Field of the Invention
This invention generally relates to devices and methods for heart valve repair and, more particularly, to endovascular devices and methods for interventional repair of the mitral valve via the coronary sinus.
2. Description of the Related Art
Heart valve regurgitation occurs when a heart valve does not close tightly, thereby allowing blood to flow backward in the heart. Heart valve regurgitation typically occurs in the mitral valve, located between the left atrium and left ventricle, or in the tricuspid valve, located between the right atrium and right ventricle. Regurgitation in the mitral valve may result from changes in the geometric configurations of the left ventricle, papillary muscles and/or mitral annulus. Similarly, regurgitation in the tricuspid valve is caused by changes in the geometric configurations of the right ventricle, papillary muscles and/or tricuspid annulus. These geometric alterations result in mitral and tricuspid leaflet tethering and incomplete coaptation during systole.
Heart valve repair is the procedure of choice to correct heart valve regurgitation of all etiologies. With the use of current surgical techniques, it has been found that between 40% and 60% of regurgitant heart valves can be repaired, depending on the surgeon's experience and the anatomic conditions present. Heart valve repair is generally preferred over heart valve replacement due to better preservation of cardiac function and reduced risk of anticoagulant-related hemorrhage, thromboembolism and endocarditis.
In recent years, several new minimally invasive techniques have been developed for repairing heart valves without the need for surgery. Some of these techniques involve introducing systems for remodeling the mitral annulus through a blood vessel known as the coronary sinus. The coronary sinus commences at the coronary ostium in the right atrium and passes through the atrioventricular groove in close proximity to the posterior, lateral and medial aspects of the mitral annulus. Because of its position adjacent to the mitral annulus, the coronary sinus provides an ideal conduit for positioning and deploying an endovascular prosthesis to reshape the mitral annulus.
One example of a minimally invasive technique for mitral valve repair can be found in U.S. Pat. No. 6,402,781 issued to Langberg et al. (“the '781 patent”). The '781 patent describes a prosthesis deployed into the coronary sinus via a delivery catheter. The prosthesis includes an elongate body, a forming element and a lock. After the prosthesis is deployed in the coronary sinus, the forming element is withdrawn proximally to adjust the shape of the elongate body and thereby reshape the coronary sinus and mitral annulus. After sufficient adjustment, the forming element may be locked to hold the elongate body in a desired shape.
Despite the recent developments in the field of minimally invasive mitral valve repair, an urgent need still exists for an improved device that can be more easily and more reliably manipulated within the coronary sinus for reshaping the mitral annulus. It is also desirable that such a device allow the mitral valve to be reshaped in a precise and controlled manner for improving valve function and minimizing or eliminating regurgitation. Additionally, there is a need for a device that can be adjusted within the coronary sinus after a period of time has passed from the initial insertion, either to increase or decrease the amount of tension they apply to the coronary sinus. Still further, there is a need for a device that is less traumatic to the coronary sinus, both during and after their insertion into the coronary sinus, and also for a device that is reliable over long periods of time. The present invention addresses these needs.